Overview
Hussain and colleagues tested whether foliar seed-water extract of Nigella sativa could mitigate cadmium stress in maize grown in Cd-spiked soil. This is a mitigation and soil-to-plant pathway paper, not cumin or black-cumin occurrence evidence: Nigella seed extract is the intervention, and the measured heavy-metal endpoint is Cd accumulation in maize leaves.
Key numbers
The starting soil was collected from nearby agricultural land with no known Cd toxicity. The paper reports clay-loam soil, pH 8.2, organic matter 0.87%, electrical conductivity 1.51 dS m-1, nitrogen 0.031%, available potassium 140 mg kg-1, available phosphorus 8.00 mg kg-1, and non-detectable Cd before spiking.
The experiment used two maize genotypes, synthetic Neelum and hybrid P1543. Soil Cd treatments were 0, 4, 8, and 12 mg Cd kg-1 soil, using cadmium chloride mixed into the soil before planting. Nigella sativa seed-water extract treatments were 0%, 10%, and 20% w/v; 10 g or 20 g seed powder was boiled in 100 ml water for 45 minutes, then applied as foliar spray at 25 and 45 days after sowing. Each treatment had four replications, with two pots considered one replicate.
Table 3 reports maize-genotype marginal means:
| Treatment | Chlorophyll content (SPAD value) | Leaf area (cm2) | Shoot dry weight (g) | Plant height (cm) | Relative water content (%) | Cd accumulation (mg kg-1) |
|---|---|---|---|---|---|---|
| Synthetic | 44.7 +/- 2.0 | 1498.8 +/- 7.7 | 4.30 +/- 0.3 | 43.44 +/- 1.4 | 70.71 +/- 5.0 | 0.27 +/- 0.0 |
| Hybrid | 47.7 +/- 1.6 | 1773.3 +/- 31.9 | 5.20 +/- 0.3 | 41.08 +/- 1.6 | 61.71 +/- 3.2 | 0.23 +/- 0.0 |
| LSD at 5% | 1.72 | 23.24 | 0.31 | 1.39 | 3.73 | 0.01 |
Table 3 reports Nigella sativa seed-water-extract marginal means:
| NSE treatment | Chlorophyll content (SPAD value) | Leaf area (cm2) | Shoot dry weight (g) | Plant height (cm) | Relative water content (%) | Cd accumulation (mg kg-1) |
|---|---|---|---|---|---|---|
| 0% | 43.9 +/- 1.7 | 1629.2 +/- 24.1 | 4.47 +/- 0.3 | 39.00 +/- 1.5 | 62.48 +/- 4.8 | 0.22 +/- 0.0 |
| 10% | 46.3 +/- 1.4 | 1666.2 +/- 22.3 | 4.75 +/- 0.2 | 42.50 +/- 1.6 | 66.69 +/- 3.8 | 0.25 +/- 0.0 |
| 20% | 48.4 +/- 2.3 | 1612.8 +/- 12.9 | 5.04 +/- 0.4 | 45.29 +/- 1.5 | 69.47 +/- 3.7 | 0.27 +/- 0.01 |
| LSD at 5% | 2.10 | 28.47 | 0.37 | 1.70 | 4.56 | 0.01 |
Table 3 reports soil-Cd-dose marginal means:
| Soil Cd level | Chlorophyll content (SPAD value) | Leaf area (cm2) | Shoot dry weight (g) | Plant height (cm) | Relative water content (%) | Cd accumulation (mg kg-1) |
|---|---|---|---|---|---|---|
| 0 mg Cd kg-1 soil | 50.8 +/- 1.7 | 1857.6 +/- 23.6 | 7.60 +/- 0.2 | 49.94 +/- 1.8 | 80.73 +/- 4.1 | 0.42 +/- 0.0 |
| 4 mg Cd kg-1 soil | 48.4 +/- 2.6 | 1731.6 +/- 30.9 | 4.79 +/- 0.2 | 45.44 +/- 1.3 | 75.89 +/- 3.3 | 0.31 +/- 0.0 |
| 8 mg Cd kg-1 soil | 44.1 +/- 1.3 | 1557.3 +/- 9.5 | 3.88 +/- 0.5 | 39.94 +/- 1.8 | 69.12 +/- 5.4 | 0.31 +/- 0.0 |
| 12 mg Cd kg-1 soil | 41.7 +/- 1.6 | 1397.8 +/- 15.1 | 2.73 +/- 0.4 | 33.72 +/- 1.1 | 39.12 +/- 3.5 | 0.42 +/- 0.0 |
| LSD at 5% | 2.42 | 32.87 | 0.43 | 1.96 | 5.27 | 0.02 |
The results text states that synthetic maize had higher shoot Cd concentration than hybrid maize, that NSE did not lower shoot Cd concentration in synthetic maize, and that 20% NSE significantly lowered shoot Cd concentration in hybrid maize. The same paragraph states that higher Cd concentration produced higher shoot Cd concentration in both maize types relative to control. These statements are retained as the authors’ interpretation, while the marginal Table 3 Cd values are reported as printed.
Methods (brief)
The experiment used free-draining plastic pots with 8 kg soil capacity. Cd treatments were produced by mixing cadmium chloride into soil before planting. Four seeds were sown per pot, and Nitrogenous and phosphatic fertilizers were applied at 100 and 75 mg/kg soil. Plants were harvested at 75 days after sowing for growth traits.
Leaf Cd accumulation was measured in the same leaves used for relative-water-content determination. Dried leaves were ground to fine powder, digested by a two-step acid-digestion method, and analyzed on an atomic absorption spectrometer, reported by the paper as iCE9 3000 SERIES. Cd accumulation is presented as mg kg-1 of plant biomass. The paper reports cadmium only and does not measure Pb, As, Hg, or Cr.
Implications
Certification: Do not use these values as market maize occurrence or black-cumin occurrence. The maize was grown in deliberately Cd-spiked pot soil, and Nigella sativa seed-water extract was used as a foliar intervention.
Courses: Useful controlled-study example of Cd soil stress, leaf Cd measurement, genotype differences, and plant-extract mitigation claims. The Table 3 marginal Cd values and the authors’ narrative interpretation should be taught together because they do not line up cleanly.
App: Context only. This source supports remediation/pathway narrative for cadmium-contaminated agricultural soil and plant uptake, not consumer-facing product scoring.
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Verification notes
Recovered from skip:not-food-occurrence under the 2026-06-10 inclusion-by-default rule. The old skip treated the file as non-occurrence because the fetched ingredient label was cumin, but the paper is in-scope as a2 mitigation/remediation and a3 soil-to-plant transfer evidence: it measures Cd in maize leaves from Cd-spiked soil and tests a foliar intervention.
Numbers were checked against the extracted PDF text, especially the abstract, experimental treatment description, acid-digestion section, Table 3, Cd-accumulation results paragraph, and conclusion. Units were copied as printed (mg Cd kg-1 soil and mg kg-1 of plant biomass) without conversion. Products and ingredients are intentionally empty because no market food product or ingredient occurrence was measured.
Update history
The five most recent substantive edits to this page, classified major (evidence or structure moved), correction (a published value or statement was wrong and has been fixed), or minor (narrative rewritten without changing the underlying evidence). Each description is derived from what the edit did to this page; the linked commit is the authoritative record, routine regeneration passes are excluded, and the full version history lives in git. When DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.